The invention relates to a method and apparatus for rotating an article, more particularly f or rotating a folding carton having the shape of a cuboid.
It is known for packaging machines to first of all set the carton blank upright in such a way as to form the bottom section, and the longitudinal and end wall sections of the folding carton which are disposed perpendicularly thereto. The longitudinal wall sections and transverse wall sections are joined together by, for example, stapling or gluing end wall sections to one another. As a general rule these operations are carried out while the carton blank is being carried along in a direction in which the longitudinal wall sections, seen in longitudinal extension thereof, are conveyed in the conveying direction. The lid section is then bent back and thus closes the opening in the loaded folding carton. It now only remains to fold down wall sections, which are hinged to the lid section, from their horizontal alignment into vertical alignment and to join them to the end wall sections, for example by stapling or gluing them. So that these final operations in forming the folding carton can be done from the side, based on the direction in which the folding carton is being conveyed, it is necessary to first rotate the folding carton about a vertical axis, in particular through 90xc2x0.
From EP 0 074 129 there is known a method for rotating an article that has a lower surface and lateral surfaces, in particular for rotating a folding carton in the shape of a cuboid, wherein the article is conveyed along a first lane, is turned to enable the article to be re-aligned and is carried along a second lane which runs in the direction of the first lane; the rotation of the article takes place under the action of an element that is in contact with one lateral surface of the article. There the element in contact, hereinafter referred to as the contact element, is horizontally aligned and mounted so as to be able to pivot about a vertical axis in such a way that the contact element is permanently revolving and the speed at which it revolves is harmonised with the speed of travel of the individual, partially formed folding cartons being continuously conveyed by the packaging machine. In the case of the foregoing apparatus for rotating the article, the first lane is laterally offset with respect to the second lane towards the apparatus for rotating the article. The article to be rotated, which is aligned lengthways in relation to the direction of travel of the first lane, arrives in the zone of the contact element, which moves against the leading area of the side wall section of the folding carton and thereby causes excursion of the folding carton relative to the first lane""s direction of travel. Disposed above this lane is a friction plate with brushes which make contact with and brake the lid area of the folding carton as it passes through the packaging machine; the action of the brushes may be seen as a kind of torque which provides the principal contribution to rotating the folding carton. The contact element which carries on swivelling, continuing to bear against the longitudinal wall of the folding carton, has the effect of causing a further excursion and thus rotation of the folding carton, until said contact element has reached a position perpendicular to the direction of travel of the first lane. Complete rotation of the folding carton is brought about by means of driving dogs belonging to the second lane. A first driving dog of the second lane, disposed on the side of the lane that is nearest to the contact element, trails behind and comes up against the trailing longitudinal wall section of the folding carton and carries the latter along. The driver on the other side of the second lane only subsequently comes into contact with the trailing longitudinal wall section, with the result that the folding carton, which has now been rotated through 90xc2x0, is conveyed onward by the pair of drivers, before also being closed in the region of the end wall sections.
This method and apparatus for rotating the article have the drawback that the contact element only brings about an ancillary rotational movement to produce initial excursion of the folding carton from its direction of travel and makes contact with one longitudinal wall section of the packing box. The principal rotational movement of the folding carton, on the other hand, is initiated by the brushes. Besides, it is absolutely crucial for the complete rotation of the folding carton through the desired 90xc2x0 to be accomplished by means of the trailing driver on the second lane. As a consequence of all this, the folding carton needs an extremely long conveyor line in order for it to be rotated. This in turn means that the packaging machine must have a great constructional length and this entails increased costs, both from the point of view of the space taken up by the packaging machine and from the point of view of the costs of building the packaging machine. A further drawback is the fact that it is only possible to convey at relatively low conveying speeds, for the diverse constructional elements outlined above for rotating the article need to be harmonised in terms of their motion. Apart from this, the contact element bears with friction against the folding carton, which means that it is not impossible for the folding carton destined to be swung out by means of the contact element from the direction of travel to be damaged in the associated long wall section or at least for the quality of its surface to be impaired.
Methods and machines for rotating an article, in particular for rotating a package or folding carton in the shape of a cuboid, are also known from EP 0 367 940 B1, EP 0 472 984 A1, DE 196 36 981 A1, U.S. Pat. No. 4,085,839 and U.S. Pat. No. 5,660,262.
It is the object of the present invention to indicate a method and apparatus for rotating an article, by which it is possible for the article to be rotated within an extremely confined space even at a high conveying speed.
The object is achieved by a method for rotating an article that possesses an underside and lateral surfaces, more particularly for rotating a folding carton in the shape of a cuboid, where the article is conveyed along a first lane, is turned to enable the article to be re-aligned, and is conveyed along a second lane which runs in the direction of the first lane, and the rotation of the article takes place under the action of an element that is in contact with a lateral surface of the article; the crux of the invention is to be seen in the fact that the element is moved in the direction of the lanes, being moved against the rear lateral surface of the article, based on the article""s direction of travel, and makes rolling contact with the latter.
In the case of the apparatus according to the invention, the contact element is thus not adapted to rotate about a fixed axis, but is moved in the direction of the lanes. It is thus able to follow the movement of the article in the direction of travel as the article, notably the folding carton, is being conveyed through the packaging machine, and operates permanently on said article. This action is a rolling action, readily enabling a relative movement to take place between said article and the contact element as the article is rotating. The fact that the rolling contact does not generate friction forces between the contact element and the article ensures that the lateral surface of the article, against which the contact element bears, does not become damaged or its appearance impaired from an aesthetic point of view. The rolling contact with the article is an essential pre-requisite for the packaging machine to be operated at high conveying speeds.
The method in accordance with the invention is also distinguished by the fact that the contact element is moved against the rear lateral surface of the article, based on the article""s direction of travel. As the article is being conveyed by means of the first lane into the area of the rotation device, it is grasped from behind in this area by the contact element, via which as the contact element moves towards the lanes the point of application of the contact element on the article induces a torque in the latter, the result of which is to transmit a pushing force into the article. This force causes the article to immediately rotate in the shortest possible area. The rotation of the article can thus be brought abuot solely and exclusively by means of the contact element. It is preferred if in order to rotate the article the contact element is moved against the rear lateral surface of said article, adjacent to a lateral surface of the article that extends towards the lanes, thereby producing an eccentric point of application of the contact element against the article. Ancillary means that contribute to the rotation of the article may be provided. Thus, for example, as the article rotates the area of the article that is situated opposite the region in which the contact element and the article are in contact may be conveyed more slowly with a component of motion towards the lanes than is the contact area, by virtue of the fact that friction acts upon the side of the article that is situated opposite the contact area, and/or the lower face and/or the upper face of the article.
Particularly when a folding carton in the shape of a cuboid is to be rotated, it will be standard procedure for the rotation of the article to produce re-alignment of the article turned through approx. 90xc2x0.
One preferred refinement of the method according to the invention proposes that a supporting element be moved towards the lanes, the supporting element, based on the direction of motion of the contact element, being disposed to the rear thereof, and the rear lateral surface of the article being in rolling contact with said supporting element as it is re-aligned. Thus, for instance, it is a particular problem to guide the newly aligned article in a stable manner. In the case of conventional packaging machines this is done by means of lateral guide rails as a general rule. However, these follow the contours of the machine""s rotational area and necessitate a very great constructional length. In addition there is the fact that as a general rule the complete rotation of the article is effected by the driving dogs belonging to the second lane which were described in the introduction in the discussion of the prior art; this likewise has the drawback of increasing the constructional length of the machine. The presence of the supporting element means that it is not necessary for the rotated article to be guided on the side of the rotation device by means of guide rails. Instead, it is the contact element which causes the article to rotate. Once the article has been rotated into the newly aligned position, the supporting element makes additional, rolling contact with the rear lateral surface of the article, which following rotation is now disposed laterally, based on the article""s direction of travel. The distance between the contact element and the supporting element ensures a lateral guide for the article which moves with the article. At this instant the article is already moved onwards by means of the second lane, thereby enabling the lateral guide to convey it by means of the contact element and the supporting element in a straightforward manner into the zone of a flush lateral guide on the second lane, which is configured in the manner of a guide rail.
In accordance with one special feature of the method according to the invention, provision is made for the contact element and/or the supporting element to travel in a revolving fashion. This is intended for use particularly where a plurality of contact element and supporting element pairs are joined to a chain conveyor.
At least when the rotational movement of the article ends, it must be ensured that the latter is guided on the side of the packaging machine that lies opposite the rotation device. This can be done by a guide rail aligned substantially in the direction of travel. The guidance of the article may be optimised in this zone, thereby even helping to rotate the article by the fact that as the article rotates the vertical edge thereof that is diametrically opposed to the contact area of the contact element is introduced between two rollers adapted to rotate about vertical axes, the rollers making contact with the two lateral surfaces contiguous with this vertical edge. Thus as the article is conveyed, a quasifixed point about which the article is rotated is created on the side opposite the rotation device; the contact element moves the area of the article nearest thereto in the direction of travel and consequently pivots the article about the fixed point. The freely rotatable bearing of the rollers makes it possible to operate on both lateral surfaces of the article in the vicinity of the vertical edge without damaging it. Thanks to the unimpeded slight roll-off action on the lateral surfaces of the article, the rollers are able to execute compensating movements during the rotation. The article is thus held laterally exclusively by means of the various rollers. The leading roller in the direction of travel conveys the article into the vicinity of a further guide rail by means of the second lane, thereby guiding the rotated article in the vicinity of the two end faces as it is conveyed onward through the packaging machine. The onward transfer of the article for example takes place in the conventional manner using drivers which engage behind the article in the area of the trailing longitudinal wall.
Particularly when articles are conveyed at a relatively low speed through the packaging machine, as a general rule the rotation of the article will already have been achieved after a very short conveying distance, that is to say before the vertical edge of the article is introduced between the two rollers. From this point of view a guide for the vertical edge of the article diametrically opposed to the contact area of the contact element should also be provided before the area of the two rollers. Since the article is still being rotated, this guide does not need to be arranged parallel to the direction of travel, but may stretch conically towards the trailing rotatable roller relative to the direction of travel. Conversely, at high conveying speeds the location of the two rollers should be harmonised in such a manner that the vertical edge is introduced between the two rollers.
One preferred design of the apparatus for carrying out the method according to the invention provides for the contact element to be mounted in a revolving conveyor device which has a conveying line running parallel to the direction of travel of the first lane in the direction of travel thereof; the contact element has a freely rotatable roller. Preferred refinements of the apparatus, relating to the design of the supporting element, the mounting of the contact and supporting element in the conveyor device, the arrangement of the two lanes and the device for facilitating the rotational movement imparted to the article by means of the contact element, are detailed in the subsidiary claims.
The invention thus proposes a method and apparatus that ensures that an article is rotated within an extremely small space at a high travelling speed. This is basically done by means of the contact element. The rotational action may be helped by a device that operates on the article and brings about a braking effect. In addition the counter-bearing represented by the two rollers may be provided, between which the article""s vertical edge defined above is introduced. All this helps to enable the article to be rotated in an extremely small space even at particularly high travelling speeds. This makes it possible to construct a packaging machine of very small constructional length compared to rival products, thereby resulting in low building costs.
Further features of the invention are represented in the subsidiary claims, in the Description of the Figures, and in the Figures themselves, it being noted that all individual features and all combinations of individual features are essential to the invention.